Dock weather barriers (weather barrier apparatus), such as dock seals and dock shelters, address the need to prevent the ingress of outdoor environmental conditions or contaminants (e.g., rain, snow, wind, hot/cold temperatures, insects, animals, etc.) into the interior of a building and cargo area of a vehicle during the loading or unloading of the vehicle. Dock shelters and seals also address the need to prevent the egress of conditioned air from within a building and/or a vehicle cargo area to the outdoor environment. Examples of dock seals and/or shelters with various header structures and side structures are disclosed in U.S. Pat. Nos. 6,205,721; 6,233,885; 7,185,463 and 8,307,588.
Some known dock seals use side members having a compressible foam core or body surrounded by a coated fabric or vinyl outer layer. The foam core provides sufficient structural rigidity to enable the side members to be extended a short distance from the building wall surrounding the loading dock. The coated fabric outer layer protects the foam core from outdoor environmental conditions (e.g., moisture), provides wear resistance to repeated impacts from the rear portions of vehicles, and may provide desirable aesthetic qualities. Additionally, a header structure may span between and/or above the side members and is installed along a top portion of the loading dock opening. The header structure may be another compressible member similar in construction to the side members and, in some cases, may include a weighted fabric curtain that hangs downwardly to contact the top of a truck trailer to form an environmental barrier along the top of the trailer.
Another type of dock seal uses inflatable side members and a header structure having internal compressible resilient pads, which provide some degree of side member compressibility when the side members are in a deflated condition. In either case, when the rear portion of a vehicle (e.g., a truck trailer) is backed into either foam or inflatable dock seal side and header members, the side and header members are compressed toward the building wall to form a seal along the lateral and top back edges of the vehicle. If present, the head curtain sweeps along the top of the trailer to form a seal at the top of the trailer between the side members. Dock seals typically consume a relatively small amount of wall space and can provide a relatively high quality seal between the rear edges of a vehicle and the outside building wall surrounding the dock. However, when the dock seal side members are compressed, they may be displaced into or otherwise encroach on the opening to the rear of the docked vehicle. As a result, the compressed side member may interfere with operation of a fork lift and/or an operator during loading and unloading activities. In addition, inflatable dock seals are susceptible to power losses and tears that compromise the ability of the side members to inflate to provide an acceptable seal.
In contrast to dock seals, some known dock shelters use side members that are mounted to the outside building wall surrounding the loading dock. The side members are spaced well to the outside of the sides of a docked vehicle. The side members are configured to extend (i.e., to be cantilevered) an appreciable distance from the outside building wall, particularly in cases where a dock leveler protrudes from the dock opening. The side members may also support flexible seal members or side curtains extending inwardly from the side members across at least a portion of the opening defined by the side members. When a vehicle such as, for example, a truck trailer, is backed into the opening of the dock shelter, the inwardly facing edges of the seal members or side curtains resiliently deflect and sweep against the lateral sides of the trailer to form an environmental barrier therebetween. As with dock seals, dock shelters also typically include a header structure, which may include a head curtain, to form an environmental barrier along the top edge of the rear of the vehicle.
In contrast to dock seals, dock shelters typically provide unobstructed access to a vehicle cargo area opening (i.e., there are no foam pads or the like to be compressed and displaced into the opening). However, most known dock shelter side members are constructed using rigid wood, fiberglass or metal frames capable of supporting the significant weight of the seal members or side curtains, which are usually held at an appreciable distance (e.g., several feet) from the building wall. Such side members may be permanently deformed if they are impacted by a vehicle. Accordingly, bumpers or stops may be mounted to the lower edge of the dock shelter to prevent a vehicle (e.g., a truck trailer) from impacting and damaging the rigid shelter.
The rigid side members used to implement these known dock shelters are also typically mechanically coupled via the header and/or another rigid member to provide increased lateral rigidity to the dock shelter to minimize the ability of the side members to move from side-to-side. Because of this, the side members typically have to be mounted relatively far apart to accommodate a wide range of possible off-center vehicle positions. This relatively large distance between the rigid side members consumes a significant and, thus, expensive amount of building wall space for each loading dock opening.
More recently, dock shelters having impactable side members have been developed. The impactable side members are similar to those used with dock seals and typically use a foam core or body surrounded by a coated fabric outer layer. Seal members or side curtains, which may be constructed using a fabric and flexible fiberglass stays combination or a foam core and fabric combination, are typically mounted to the side members to extend at least partially across the shelter opening. When a vehicle is backed into the shelter, the inwardly facing edges of the seal members or side curtains deflect and sweep against the sides of the vehicle to form an environmental barrier or seal against the sides of the vehicle. In the event the off-center position of a vehicle results in the rear of the vehicle impacting a side member, the foam core or body of the side member is resiliently compressed. When the vehicle is pulled away from an impacted side member, the foam core of the side member causes the side member to substantially recover to its original condition or shape.
The areas of a loading dock shelter where the side seal members and the header's upper seal member meet and interact can cause sealing and wear problems. In some instances, a relatively stiff head curtain or other header sealing member will interfere with the side seal member's ability to seal along the vehicle's rear edge, near the roof of the vehicle. Because the upper seal member of a header structure is generally wider than the widest truck, the upper seal member overlaps the upper portion of the side seal members. As the vehicle pushes the lower edge of the header's upper seal member back towards the dock, the lower corners of the header's upper seal member will contact and push the face of the side seal member away from the side of the vehicle, thereby preventing a good seal in that area. There can also be excessive wear on the portion of the upper seal member that overlaps the side seal member. As the vehicle backs in and penetrates the weather barrier apparatus, the header's upper seal member can be pinched and dragged between the vehicle and the side seal members. This often causes premature wear on the side seal members.